This invention relates to a high-pressure ball valve which includes a housing having a valve bore communicating with an outlet bore at the periphery thereof and an inlet bore having a seat surface facing the valve bore; and a valve member formed with a bore receives a stem mounted for actuation by a hydraulically-actuated piston to move and hold a ball against the seat surface for closing the inlet bore.
In West German patent publication No. DE-OS 29 47 551, there is disclosed a high-pressure valve including a housing formed with an inlet and an outlet and a valve member displaceable between the inlet and outlet by means of a drive. The valve member is guided in a ball cage and is constructed as a ball adapted to be lifted from a seat surface therefor against fluid pressure by a valve stem connected to the drive. The stem is guided in a cylindrical bore extending from the valve seat. Axial recesses in the cylindrica1 periphery of the valve stem allow the fluid medium to pass to a housing chamber. An axial extension of the valve stem merges into a piston rod which includes a piston that can slide in a cylindrical bore in the valve housing. A hydraulic, pneumatic or electric drive reciprocates the piston in the cylindrical bore at a required frequency to open and close the valve at that frequency.